1. Field
The present disclosure relates generally to surge protection circuits and improvements thereof. More particularly, the present disclosure relates to surge protection circuits with reduced voltage let through and improvements thereof.
2. Description of the Related Art
Communications equipment, computers, home stereo amplifiers, televisions and other electronic devices are increasingly manufactured using a variety of electronic components that are vulnerable to damage from electrical energy surges. Surge variations in power and transmission line voltages, as well as noise, can change the operating frequency range of connected equipment and severely damage or destroy electronic devices. Electronic devices impacted by these surge conditions can be very expensive to repair or replace. Therefore, a cost effective way to protect these devices and components from power surges is needed.
Surge protectors help defend electronic equipment from damage due to the large variations in the current and voltage resulting from lightning strikes, switching surges, transients, noise, incorrect connections or other abnormal conditions or malfunctions that travel across power or transmission lines. As the number of electronic systems and equipment increase through both commercial and industrial society, the need for adequate and efficient protection from power surges becomes ever more important. A malfunctioning system or piece of equipment due to an unexpected or unintended surge of electrical power runs the risk of extensive monetary damage to the system or equipment and can even impact human safety. In an effort to reduce these risks, protection circuits or devices have been incorporated as part of or connectible to electrical systems or equipment in order to prevent the propagation of power surges through the electronics or other electrical equipment.
Circuit elements such as silicon avalanche diodes (SADs), metal oxide varistors (MOVs), Gas Discharge Tubes (GDTs) and other non-linear circuit components have been used for diverting a surge above a predetermined threshold from a signal line. However, conventional protection circuits can be extremely costly as the power dissipation requirements for a given system increase. Such components can be prohibitively expensive for many applications, particularly when the components must be capable of withstanding significant amounts of voltage and current upon conduction of an overcurrent or overvoltage. Conventional avalanche suppressors produce significant noise and glitches during the avalanche process before reaching a full conduction mode which can upset or damage sensitive protected equipment. Conventional GDT technologies are slow in response time due to the gas ionization/excitation process that is required in order for the energy discharge to occur, and thus they can allow very high let through voltages to propagate to the protected equipment. Similarly, conventional MOV technologies have high parasitic inductances and capacitances in the package causing the slow response time. This let through voltage can be extremely harmful to equipment if left unmitigated and adds additional expense to surge protection circuitry since higher rated surge components must be utilized.
Therefore, a surge protection system or circuit is desirable that can reduce the let through voltage to a minimal level when compared to conventional circuit protection technologies and thereby provide a lower clamping voltage with better filtering of surge signals in order to efficiently prevent the propagation of overvoltages or overcurrents to protected systems or hardware. The surge protection system or circuit would also desirably reduce the cost of such protection circuitry due to the reduction of the let through voltage remnant. In addition, the surge protection system or circuit would desirably be capable of easy scalability to a variety of surge protection or suppression power requirements or filtering needs.